A conventional shock absorber comprises a piston that is inserted into a cylinder so as to be free to slide and delineates two oil chambers within the interior of the cylinder, a port that penetrates the piston and is capable of connecting the two oil chambers, a leaf valve laminated onto an outlet opening portion of the port, and a spring that biases the leaf valve in a direction for closing the port outlet opening portion (see JP2004-190716, for example).
In this type of shock absorber, the leaf valve is bent by a differential pressure between the two oil chambers, and the flow area of a passage through which a working fluid passes is determined by the bending amount of the leaf valve. A damping force generated by the shock absorber is determined according to the flow passage area.